What is 1/15 + 1/9?
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Here's how you add
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Step 1Of course, you can't add two fractions if the denominators (bottom numbers) don't match. To get a common denominator, multiply the denominators together. Then we fix the numerators by multiplying each one by their other term's denominator. Now you multiply 1 by 9, and get 9, then we multiply 15 by 9 and get 135. Do the same for the second term. We multiply 1 by 15, and get 15, then multiply 15 by 9 and get 135. The problem now has new fractions to add:
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Step 2Since our denominators match, we can add the numerators. 9 + 15 = 24 This yields the answer
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Step 3The last step is to reduce the fraction if we can. To find out, we try dividing it by 2... No good. So next you try the next prime number, which is 3... Are both the numerator and the denominator evenly divisible by 3? Yes! So we reduce it:
So far so good... let's try to divide by that number again. No good. So next you try the next prime number, which is 5... No good. So next you try the next prime number, which is 7... No good. So next you try the next prime number, which is 11... No good. 11 is larger than 8. So we're done reducing. And we're done! Here's the final answer to 1/15 + 1/9
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